The best way to make fast, easy money in Assassin's Creed 3 is to sell perfect bear pelts by naval convoy to St. Augustine. There's a couple things you need to do in order to start using this method, but once you do all this you can simply set the convoy in action, and wait for your huge profits to roll in.

First, unlock naval trade

In order to unlock the ability to perform naval trade, you must do the homestead mission for Lance when he collects his tools from Boston. This is unlocked in the 9th sequence I believe. Once you complete this the naval convoy recipe will be unlocked. You can then go to your crafting bench in the Homestead, and find the recipe in the 'Special items' section of the crafting page. The recipe for the convoy is Oak Bark, Spruce Lumber, Bear Grease, and a level 2 woodworker.There's a capacity upgrade available for the convoy as well. The recipe is Maple Lumber, Kindling and a level 3 woodworker. This will allow up to 10 items per trade.

Collect perfect bear pelts

The most valuable item to collect is bear pelts. When collecting them, try to use your hidden blade so that they are in the best condition, and fetch the best price. My favourite place to hunt bears is 'bear island' in the Frontier. Here is the location on the map:

'Bear Island', indicated by the marker on the map. North-Eastern Frontier.

Fast travel to the icon in the north part of this map and run south to this island. Here you should be able to find as many as 10 bears roaming around. Kill them all as cleanly as you can for their perfect pelts. I then fast travel back to the edge of the Frontier and run back down to reset their spawns. Repeat as often as you'd like!

Optional - reduce the risk and maximize profits!

All convoys have a risk. Even when you reduce your risk as much as possible there will still be a 5% chance that you'll come out empty handed. In order to get your risk level down to only 5%, you need to complete the naval missions which are on the way to your destination. All pelts are sold for the highest price to St. Augustine, so complete these three naval missions. They're all really fast and easy, you just need to take out a few ships.To make the most out of your convoys, you want to reduce your taxes. I liberated every fort in the game, so I have 0% tax, meaning all the profit from convoys goes to me.

Set your convoy

Go back to your homestead and start sending out your convoys. Select your naval convoy, and set it to selling 10 bear pelts to St. Augustine, which should fetch 1560 coins per pelt, if they are in the best possible condition. In 32 minutes of you'll find 15,000+ coins added to your purse. Not too bad!During this time I usually also set other convoys to other locations, with the next profitable pelts. The 5 most expensive pelts in order are; bear, beaver, elk, wolf, deer. I always have these hides laying around from hunting I've already done, so these add thousands to my profit while I'm waiting for my first convoy to return.

Guess what? This is exactly what large companies are paying for. They need to know what their customer base needs and wants. So large companies pay $1,000,000's of dollars every month to the average person. In return, the average person, like myself, answers some questions and gives them their opinion.